View
2
Download
0
Category
Preview:
Citation preview
I
NASA TECHNICAL NASA TM X.73.098' MEMORANDUM
(NASA-TM-X-730g8) 5EgEFITS OF VTOL AIRCRAFT N76-18087
i IN OFFSHOF,E PETKJLEUY_ LOGISTICS SUPPORT(NASA) 69 p HC $4.50 CSCL 01C
Unclas
G3/03 lq301
?:.4,
--: BENEFITS OF VTOL AIRCRAFT IN OFFSHORE PETROLEUM *
LOGISTICS SUPPORT
DarrellE. Wilcox and Michael D. Shovlin
Ames Research CenterMoffett Field, California 94035
-.t !
]9760]0999
https://ntrs.nasa.gov/search.jsp?R=19760010999 2020-03-22T16:26:59+00:00Z
1 I 1 1 _q
; 1
1. ReportNo. 2. GovernmentAccmionNo. 3. Rec,p*ent'sCatalogNo.
TH X-73,0984. T_tle and F>ubtitle ' - 5. ReDorl Dire
BENEFITS OF VIOL AIRCRAFT IN OFFSHORE PETROLEUH6. Performing Orgonizltlon Code
LOGISTICS SUPPORT
7. Author(s) " 8, PvforrniogOrgenizatioq_ReportNo.
Darrell E. Wilcox and Michael D. Shovlln A-6360
• 10. WorkUnit No.
9. I_rformin 90rslanicltion Name and Addrlm 791-93-14Ames Research Center i;.Contracto¢Gnmt NO.M_ffett Field, Callf. 94036
1"3.Typeof RqxxtandPerkxlCo.red
12.spomo_ng_macvNa_ _d Addrm Technical Memorandum
National Aeronautics and Space Administration I--4.soo_iog_ cod,Washington, D. C. 20546
15. SUl)ldom4ntMy Notes
16. Abject ....
The mission suitability and potential economic benefits of advancedVIOL aircraft were investigated for logistics support of petroleum opera-tions in the North Sea and the Gulf of Mexico. Concepts such as the tiltrotor and llft/crulse fan are very promising for future operations beyond150 miles offshore, where their hlgh cruise efficiency will provide say-|ings in trip time, fuel consumption, and capital investment. Depending
upon mission requirements,the aircraft operating costs may be reducedby as much as 20 percent to 50 percent from those of current helicopters.
• 17.KeyWords(Summed'byAu_ho,('a)) ' IlLmnri_n Smenmt ....
Air transportation UnlimitedAircraft propuls_.c_, and power
STAR Category - 03
' 19, IIocuHWClmif. (of_ reeort) 20. IlocurlWClmlf.(of ddepeee) _1. No.of Palm _ I_loo"
_: Unclassified Unclassified 68 $4.25 iii
"Few. IIVtheNiRionllTll¢ltnlalInformltkmIkmdlle.IlldlqllklM,Vlqlil_ 221111 i
! 'i]
] 9760] 0999-002
TABLE OF CONTENTS
' SUMM_RY I
INTRODUCTION 4
TRENDS IN OFFSHORE ACTIVITY 9
OFFSHORE SUPPORT REQUIREMENTS 14
LOGISTICS SUPPORT VEHICLES 22
BENEFITS OF ADVANCED VTOL AIRCRAFT 32
CONCLUSIONS 39
REFERENCES 42
1976010999-003
SUMMARY
The expanding search for petroleum throughout the world has created
a growing need for logistics support of exploration and production
activities. With the number of offshore wells expected to double by
1985, and with the offshore distances increasing rapidly, the requirement
for helicopters to transfer men and supplies to and from the oil and gas
rigs should continue to increase. Over 20% of the civil helicopters
produced in the next decade are expected to be utilized for this purpose.
Although marine vessels are widely used in support of offshore
petroleum, several factors have led to replacement by helicopters in a
growing number of operations. The much higher speed of helicopters
provides better emergency evacuation capability, faster parts delivery,
and increased productivity of the personnel being transferred. Beyond
about 50 miles, helicopters are the most economical means of transporting
crews. They are often used even at shorter distances, because of strong
worker preference for the speed and comfort of the helicopter. Use of
boats is particularly limited in rough weather such as that frequently
experienced in the North Sea.
A study was performed to determine the mission suitability and
potential economic benefits of advanced VTOL aircraft in offshore petroleum
operations. The North Sea and the Gulf of Mexico were selected for
analysis of advanced helicopter, tilt rotor, and llft/crulse fan aircraft
as future replacements for current helicopters. In both markets, present
use of helicopters is extensive, and projections for the 1980's indicate
a requirement for many more.
k
r
L
1976010999-004
I ! I
i
-2-
The study indicates that there is a strong need for advanced VTOL
aircraft. Performance limitations of current helicopters result in
offloading of passengers to provide sufficient fuel to reach the more
distant rigs even today. This greatly increases the unit operating cost
and the number of aircraft required. As offshore distances increase,
aircraft with greater cruise efficiency are needed to satisfy mission
requirements. Helicopters now in development will provide better
range/payload capabil±ty as well as 20% to 30% increases in cruise
speed. This will provide significant improvements in operating economics.
Further gains are possible through advanced helicopter technology now in
progress.
Future petroleum activity 200 to 500 miles offshore will require
even greater improvements in VTOL aircraft efficiency. Concepts such as
the tilt rotor and lift/cruise fan are very promising. Due to good fuel
utilization efficiency, greatly extended range of operation is possible
without refueling. The cruise speed of these concepts is also greater
than that of either current or advanced helicopters. The tilt rotor
provides nearly twice the range of the helicopter for the same fuel and
trip time. The lift/cruise fan cruises at three times the speed of the
helicopter and also yields a greater range/payload capability.
The greater productivity of such aircraft wlll provide many benefits.
The aircraft operator will benefit through reduced capital investment in
aircraft, spares, ground equipment and pllot training. Operating costs
will be reduced by 20% to 50%, depending upon mission requirements. The
petroleum industry will galn increased oll r18 productivity and improved
logistics support. Most importantly, the availability of petroleum may
1976010999-005
' _ 1 1 I 1 I ,
L
-3-
be increased by the ability to economically support exploration and
production further offshore and in more remote locations.
Each type of VTOL aircraft, as well as the boat, has a useful role
to fill in offshore oil support. For short ranges in calm seas, for
pipe laying operations, or for large cargo movement, the boat is the
most effective mode of transportation. Beyond about 50 miles offshore
or in rough weather, aircraft are more efficient, particularly for
movement of personnel and priority cargo and for emergency operations.
Tilt rotor or lift/cruise fan aircraft cannot economically replace
helicopters in the short-range operations. There will be a continuing
need for advanced helicopters for movement of small parties of executive
and specialist personnel during on-site inspections, and for crew change
operations on the many rigs close to shore. The more distant operations
, will best be performed with either the tilt rotor or lift/cruise fan, or
possibly with improved compound helicopters. The ideal fleet may well
consist of some mix of the different aircraft concepts.
1976010999-006
-4-
INTRODUCTION
In the next ten years the U. S. petroleum industry must find and
develop nearly 50% mcre oil than it did during the past 15 years to meet
our nation's increasing energy needs. (I) Projections by the National
Petroleum Council indicate a domestic oil consumption of about 26 million
barrels per day by 1985. (2) This is 40% greater than the U. S. consumption
in 1975. Such growth must be met by increased domestic oil production,
or by oil imports.
While the U. S. had a net oil import requirement of only i billion
barrels in 1968, over 2 billion barrels will be imported in 1975. This
is approximately 40% of the current U. S. consumptlon. The National
Petroleum Council has projected a range of oil import needs through 1985
based on combinations of various values for energy supply and demand
factors. The most likely combinations indicate potential imports of
from 5 to 7 billion barrels in 1985, despite increased used of coal and
nuclear energy by electric utilities.
A continuation of the 5 billlon barrel import rate would result in
a $65 billion annual cash drain from the U. S. at current oll prices.
With a 5% average annual inflation in the price of foreign oil, the U. S.
would be paying petroleum exporting countries over $i00 billion per year
by 1985. The total for all of the oll importing countries, who already
experienced a trade deficit with the oil producers of $65 billion in
1974, (3) will be many times that figure. Thus, there are strong incentives
in the U. S. and elsewhere to develop new sources of petroleum.w
1976010999-007
-5-
Some of the most promising areas in the worldwide search for oil
and gas today lie offshore. In 1974, offshore rigs produced 20% of the
world's total oil output of 50 million barrels per day. By 1985, offshore
sources may account for 25 million barrels per day. Over 400 drilling
rigs are working the world's continental shelves. (I) More than a quarter
of these are in U. S. waters, principally in the Gulf of Mexico. Major
new fields have recently been found off Brazil, in Indonesia, and in the
North Sea. Promising finds have occurred throughout the world. Stimulated
by the U. S. drive toward energy self-sufficiency, interest is increasing
on the Atlantic and Pacific Coasts, the Gulf of Alaska, and the Beaufort
Sea.
As of January I, 1974, 60 maritime nations either had or were about
to have offshore petroleum production. Offshore exploration activities
were being conducted in at least 55 additional countries. An estimated
18% of proven recoverable world reserves and as much as 60% of undiscovered
recoverable reserves may be offshore. (4) Median estinmtes of the U. S.
Geological Survey indicate that about i00 billion barrels of oil and 600
trillion cubic feet of gas remain to be discovered on the U. S. continental
shelf, about 17% of the world's undiscovered offshore total. On the
other hand, estlmstes by a major U. S. oil company place the tota]
recoverable resources off U. S. coasts at only about one-half the U.S.G.S.
(5)value, but also estimate this to be three to four times the recoverable
resources onshore.
The push for oll exploration and production offshore and in remote
locations such as Indonesia and Alaska's North Slope have created tremendous
demands for logistics support. There are perhaps 20,000 men working the
I
] 9760] 0999-008
-6-
offshore rigs around the world. These men must be transported to and
from the rigs every week or two, with an equal number replacing them.
Equipment and supplies must be provided on a timely basis to maintain
continuous operation. Rapid transfer of supervisory and trouble-shooting
personnel to and from the rigs, and emergency evacuation of sick or
injured workers are frequently required.
The petroleum industry has found that much of this support requirement
can be met very effectively by helicopters, because of their advantages
over boats in speed, operating economics, and comfort. The result has
been a rapid expansion in the use of helicopters to transport men and
equipment to the operating sites, and over 20% of all clvil helicopters
produced now and in the next decade are expected to be employed in support
of the petroleum industry. (6'7)
In some regions the helicopter is the most viable means of trans-
portation. One example is Indonesia, which is experiencing continued
demand for new drilling sites all along the 3000 mile chain of islands.
The logistics support of these operations is greatly complicated by the
terrain, which is mountainous and is covered with dense Jungle and
numerous unbridged rivers. Indonesia's ground transportation system is
underdeveloped and in places nonexistent, particularly on the ouLer
islands. Thus, the helicopter offers the only practical means of reach-
ing some of the drilling sites both offshore and in the Jungle.
In other areas, ground or water transportation is readily available.
In such cases the preferred mode of transportation is determined by
mission effectiveness and economics. Examples of this are found in the
1976010999-009
-7-
Gulf of Mexico, off tile Southern California Coast, and in the Persian
Gulf and the North Sea. Both boat and helicopter are used in these
areas.
Future requirements for offshore oil support will be dictated by
the pace of drilling activity, by trends toward increasing offshore
distances, and by labor demands for more frequent returns to home base.
Site-related factors such as weather conditions, political Jurisdictions,
and proximity to major population centers will be important in dete_ining
tbe extent of aircraft usage and geographical preferences for particular
aircraft performance characteristics.
A study of the benefits of VTOL aircraft in the offshore application
has been made to assist the identification of promising aircraft technologies
for NASA to pursue. Included is an examination of the current market in
which helicopters and boats provide support service, and also an analysis
, of the future potential for advanced VTOL aircraft with greater speed
and range than current helicopters. The study addressed the general
mission suitability and economics of advanced helicopters as well as
those of tilt rotor and lift/cruise fan aircraft. Comparisons were made
of fleet size and capital investment requirements, of the productivity
and operating costs of the candidate concepts, and of benefits to the
petroleum industry resulting from the special characteristics of each
aircraft.
Two offshore petroleum markets were selected for the analysis. In
, both the Gulf of Mexico and the North Sea, helicopters are used extensively
at the present tiNeo Projected aircraft requirements for 1985 are much
greater, as the number of offshore wells has been estimated to be severalf
3
A
1976010999-010
-8-
(2)times that of today. There are, however, important differences in
the mission characteristics for the two areas, primarily in range and
weather cond_tlons, which determine the preferred aircraft design and
performance characteristics.
1976010999-011
TRENDS IN OFFSHORE ACTIVITY
In the past the offshore petroleum industry has moved out from
inland and protected waters in an evolutionary manner. The technology
resulting from this steady growth has enabled the industry to open new
fields far offshore and In unprotected waters around the world. Offshore
operations are expensive, however, with costs running two to five times
those of onshore operations. The costs are even greater in the harsh
environment of the North Sea and the Gulf of Alaska.
Offshore Operations in the United States
Most of the current U. S. offshore petroleum exploration and pro-
duction activity is concentrated in the GuJf of Mexico, off Louslana and
Texas. Other U. S. offshore activity is located along the Southern
California Coast and in the Cook inlet area of Southern Alaska. Recentr
' geological surveys indicate potentially large oil and gas fields along
the Atlantic, Pacific, and Alaskan Coasts. One of the largest of these
fields Is thought to be located off the north shore of Alaska. However,
the technical problems resulting from foul _eather and Ice flows In the
Arctic Ocean and Beaufort Sea wlll probably prevent any significant
development during the 1980's.
The Hobll 011 Company estimates the total recoverable reserves
located on the continental shelf of the U. S. at 48 billion barrels of
oli. (5) About 14 bllllon barrels are thought to be located In the Gulf
, of Hexlco and s llke amount In the Gulf of Alaska, mostly st eater
depths of Isss than 1500 feet. In addition, Atlantlc reserves are
estimated st 6 bl111on bsrrels snd Pacific reserves at 14 billion barrsls,
]
1976010999-012
-10-
based on exploration in water depths ranging to 6000 feet. Numerous
geologic surveys have been conducted along the Atlantic and Pacific
Coasts and in the Gulf of Alaska. The rate which these areas will be
opened for dev. iopment is dependent to a large extent on political
factors in addition to the normal economic and techni, t considerations.
(;ulf of blexico
The boundaries of current and future offshore activity in the Gulf
of Mexico are shown in Figure 1. Most of the 100 drilltnz rigs now
operating are in offshore Lousiana waters, although several large new
areas were recently opened for exploration of Florida and Texas. Futr"',
activity will expand into the potential new lease areas shown in Figure
(8)l. Extending operations into this area would increase maxim,.awater
depth from 600 to 1500 feet and would increase the distance from shore
bases well beyond the 150 miles to which current activity is restricted.
There are in excess of 6600 producing oil wells and 2700 gas wells
offshore in the Gulf of Mexico. New wells were being drilled at the
rate of over 900 per year In 1973, and activity is at a much higher rat_
in 1975. The number of drillllng rigs in the Cull is now about I00, an
increase of 20 percent from 1974. (9)
Southern Californla
Activity off the Southern California Coast is shown in Figure 2.
Present offshore operations are centered around the Santa Barbara Channel.
Surveys of the Outer Santa Barbara Channel and the Pacific Ocean near
San Diego have been conducted and drllllng Is expected to begin as soon
as leases and government permission can be obtained.
JI
1976010999-013
-II-
Most of the 2800 producing oil wells are within 35 miles from shore
and the majority of production islands are less than i0 miles from
shore. However, with the opening of the outer channel the offshore
distances will reach 50 to I00 miles. These offshore operations will
establish a production distribution network which will eventually
provide a basis for more distant offshore development in waters as much
as 6000 feet deep.
Offshore Alaska
Current and future Alaskan offshore activity is shown on Figure 3.
Present activity is centered in the Cook Inlet on the southern coast of
Alaska, where recovery operations have had to overcome icy waters and
very high tides. Surveys indicate approximately i0 billion barrels of
oil under the Gulf of Alaska and 4 billion barrels _- the Bristol Bay
area. (2) Cost of operations in these areas will be significantly higherI
than those in the Cook Inlet and the distances from current population
centers would be as much as i00 to 200 miles.
The oil reserves in the offshore area of the North Slope are
estimated as high as 48 billion barrels. However, the extreme cold, the
stormy and icy seas, and the l_mitcd drilling season make exploration
and production operations extraordinarily costly and difficult. The two
greatest offshore obstacles are ice flows and polar pack movements that
often scour the sea bottoms. Due to the enormous costs that would be
I: required and the time needed to develop the required technology to
_ operate under these conditions, it is unlikely that any of this potential
will be developed during the next 15 years.
1976010999-014
...........,............T...................,.....................................7-...............I.............................................".................................T..................................._.........................................,'"[ r i
,' I ' iI' : I iI
-12-
Atlantic Coast
The location of several promising potential gas and oil development
areas off the Atlantic Coast are shown in Figure 4. The initial exploration
is expected to begin in the Ceorges Bank area, where Canadian oil companies
have a]ready located two gas fields off the coast of Nova Scotia. Offshore
distances fro_ the North Atlantic and Middle Atlantic states are expected
to range from 30 to 150 miJes with somewhat greater distances and water
(to)depths off the Florida Coast. The main obstacles to Atlantic exploration
and development are jurisdictional disputes between the Atlantic Coast
states and the federal government over control of the oil and gas deposits
and environmental concern over drilling off the Atlantic Coast.
North Sea Petroleum Operations
The discovery of the Ekof_sk oil field by Norway in 1969 gave a
rapid stimulus to exploration and development in the North Sea. Since
that time two more major oil fields have been discovered: the Forties
Field about 120 miles east of Aberdeen, Scotland, and the giant British-
Norwegian fields which are more than 150 miles northeast of the Shetland
Islands. Figure 5, from reference ii, shows current activity in the
British and Norwegian sectors and the location of the major oll fields
and some of the exploratory activity out of the main supply port of
Aberdeen and the forward staging area of Sumhurgh. Distances range from
slightly less than i00 miles to nearly 200 miles.
A large number of oil discoveries near these fields are awaiting
production. Ultimate North Sea reserves have been estimated to be -'n
the order of 42 billion barrels of oil and 110 trillion cubic feet of
" "J " 'v...........;"_ _ _""_........................Ir......_'_ _r "......T......-_.._,_.w_._,_.................................T ......................mr....i
1976010999-015
I ! ! '
-13-
(12)gas. It has been further estimated that the North Sea will be
producing 4 million barrels of oil per day in 1985.
Potential future North Sea activity in relation to current activity
is shewn on Figure 6. In 1973, surveys of the Norwegian continental
shelf were made at distances out to 200 miles offshore. (13) As a result
of these surveys several blocks have been leased near the Arctic Circle
about i00 miles off the coast. In addition a high level of future
activity in the British sector of the North Sea was assured by the 197Z
award of 246 blocks in the North Sea, the Atlantic Ocean west of the
Shetland Islands, and in the Celtic Sea. (12)
IL
I
1976010999-016
-14-
OFFSHORE SUPPORT REQUIREMENTS
When petroleum exploration first moved offshore in the 1930's, the
rigs were set on stationary platforms close to shore in the Gulf of
Mexico. Boats were used to transport men and equipment to the rigs. As
oil and gas demand increased, the exploration ventured further offshore.
Now, highly sophisticated mobile rigs work in deep water out of sight of
land, and water depths are being greatly extended. Offshore distances
presently range up to 200 miles in some areas, and distances of 300 to
500 miles may be common in the future.
Coincident with this movement is a continuing need for improved
logistics support. Helicopters have now replaced boats for many operations.
Numerous factors will influence future support requirements. Some of
the more pertinent characteristics of the offshore mission are discussed
below.
Drillln$ Technology
The modern offshore drilling fleet consists mainly of three types
of rigs: the Jack-up, the semi-submersible, and the drillship. The
Jack-up is similar to a barge and is towed to the drilling location,
where it is jacked up above the sea. About half the offshore fleet is
of this type. (1) From 30-60 men typically work aboard these rigs for
7eriods of one to two weeks before being replaced. Since Jack-ups are
less stable in deep water, this type of rig is limited to water depths
of about 300 feet. Most offshore drilling in the past has occurred in
less than 300 feet of water, but the search for oil further offshore is
increasing the average depth, i|!
For greater depths and rougher weather the semi-submersible or i
: drillshlp is required. Both are floating rigs with a system of anchors
L,
1976010999-017
-15-
tO hold their position. The more stable' semi-submersible is preferred
in tl'usevere conditions of the North Sea. The upper structure is clear
o'-th; sea, while a telescoping joint suspended beneath the drill floor
yermJ s drilling in heavy seas with 12 or more feet of heave. The
d1.11ship, on the other hand, can operate in very deep water, but is
best in calm seas. It is used in remote locations such as Indonesia,
where its capacity to store supplies allows the drillship to work at sea
for m,nths with minimum cargo support from shore.
There are from 60 to 90 men on most semi-submersibles. However,
the ne_er, larger ones, including several of those in the North Sea,
have up to 200 men. Drillships are generally in this same size range.
Most semi-submersibles and drillships are presently working in
depths of less than i000 feet of water, although some operations approach
20G) feet. The working depth of drillships is now limited by the design
of the d_-illing r4.er which connects the ship to the wellhead on the sea
floor. Nowever, improved equipment design will eventually provide the
freedom to work at practically any water Jepth. (I) This will permit
greatly increased offshore distances and will alter the required charac-
teristics of support aircraft.
Crew Transport
Crew changes on offshore rigs typically occur every one to two
weeks. ,Jutthe trend is toward more frequent rotation. Labor is beginning
4-
to :emand contracts that require transportation to and from work sites
_ at shorter intervals. Production crews are usually smaller than drilling
crews, _c "otate on the same weekly or biweekly basis. Industry
practice for compensation of workers in transit varies widely. Some
1976010999-018
' T I 1 1I
i
-16-
rompanie_ p_y legal minimum wages, some pay tile same wages for transperta-
tion and rig time, and some use other forms of compensation.
Recent growtb in the number of helicopters and boats used for
offshore oil support in U. S. waters has been impressive, as Figure 7
shows, lu 1973 there were 320 helicopters and 355 boats, of which 118
were crewboats. By 1975 the number of helicopters has risen to 460, a
44% increase. The number of medium helicopters, the type used in crew
change operations with 8 to 14 seats, has increased by 56% in that two
year span. The number of boats in 1975 is about 470, of which 129 are
crew boats. It should be noted that the total number of boats grew by
one-third, although the number of crewboats increased by only 9%. This
indicates a shifting preference in favor of helicopters for crew change
operations.
The shift from boat to helicopter as the primary means of trans-
portation was prompted from a preference by both the men and the oll
companies for the faster mode. The company incentives are the need to
increase the productivity of the oil rig crew3, and the fact that total
trip costs with helicopters are less than those of boats for distances
(14,15)beyond about 50 miles. Even at minimum wages, the cost of trans-
porting workers i00 to 200 miles offshore by boat Is excessive when time
value is included. Helicopters are often used in place of boats even
below 50 mile distances, due to the preference of oil rlg workers for
the greater speed and comfort of the aircraft.
Other forms of marlne transportation, including hydrofoils, have
been considered, but are not as efficient as the helicopter for moving
people and equipment to and from the offshore installations. Rough
i ii
J#
i
i
j
1976010999-019
-17-
weather sometimes delays crew transfer because of inability to safely
bring the boat up to the rig. In addition, several hours on a boat in
rough seas often leave the crew unable to work even after reaching the
rig. This is especially true of the North Sea, but also of other areas
during some parts of the year. Workers transported by helicopter,
however, usually arrive without delay in all but the most severe weather.
Major helicopter operators serving North Sea oil and gas rigs are
(16)averaging about 98% reliability in meeting scheduled commitments.
Emergency Operations
Besides the routine transfer of men and supplies, helicopters have
proven very useful in emergency operations. Evacuation of sick or
injured workers is a frequent requirement. Accident rates are high, and
pain-killing drugs often are not permitted on offshore rigs. One major
helicopter operator evacuates an average of one worker per night from
the Gulf of Mexico, (15) although others average only a few such trips
per month. Occasionally entire crews must be evacuated because of an
approaching storm. In such eases, speed is of the essence.
There are also numerous requirements for emergency part delivery.
Although an attempt is made to m_intain critical spares on the rigs, the
number of helicopter trips for unscheduled personnel and cargo transfer
(17)about equals the scheduled trips for some operators. With large
rigs costing as much as $50,000 per day to operate, (18) a breakdo_ is
very costly, making the expense of part delivery by helicopter well
Justified. Even with high speed boats, it would take eight or ten hours
to deliver parts to the more distant locatlons.
[ i
1976010999-020
-]8-
Another frequent use of helicopters is to transport _xe_utiv_
personnel to the rigs for onslte inspection. The time value of such
personnel is high. Since these trips usually involve sma]l parties,
small helicopters are generally used, and the aircraft stands by for
return to base.
Operations in the Gulf of Mexico
The first entry into the highly specialized business of oil field
helicopter operation was in the Gulf of Mexico in ]949. Today there are
five major helicopter operators supporting offshore operations in the
Gulf with about three hundred helicopters of various sizes. (16) There
are about 4000 oil and gas production platforms offshore, most of them
with helicopter landing platforms. (19) On such platform is shown in
Figure 8. Support bases are established all along the coast in order to
reduce trip time to the various fields, and Figure 9 shows that one
operator alone has 15 permanent helicopter bases between Tampa and
Corpus Christi. Some of these bases could probably be eliminated if
aircraft with higher speed and longer range capability were available.
While most of the helicopters used in the Gulf are small, single-
en&'ned aircraft such as the Bell 206B, there are at least 45 medlum
helicopters capable of carrying from 12 to 20 passengers. Service is
provided to rigs as close as a few miles, and as far as 150 miles offshore.
Th,- shorter trips are generally by 3 to 4-place hellcopters between
rigs. Most crew changes performed by hellcopter start at ranges of 40
to 50 miles, and the average trip distance for the medium hellcopters is
now about 105 miles. This is expected to exceed 150 mlles by 1985.
i
1976010999-021
-19-
There are currently more than 20,000 passenger round trips to the
offshore rigs each month, plus many passenger movements between rigs.
With the number of wells illthe Gulf growing rapidly, and with crew
sizes increasing for the large rigs drilling in deep waters, the number
of workers being transported by aircraft is greatly expanding. Con-
sidering the likely increase in the average range requirement, the
number of aircraft required in the late 1980's may be several times that
of the present. Crew changes occur every seven days, and many companies
are currently paying minimum wages for transit time. Spares and
emergency service are a small part of the total helicopter operation in
the Gulf, and are not considered likely to become a major part of the
operation in the future. Cargo is usually not carried by helicopter,
although each passenger is permitted to carry 25 Ibs. of baggage.
Refueling ls generally not permitted on manned rigs, so the aircraft
must divert to ur_anned platforms to refuel or be capable of round trip
operation with normal reserves. As offshore dlstances increase, larger
aircraft with a longer range and higher speed capabillty will be needed.
Operators are currently taking options on the Boeing 179 and the Sikorsky
S-78, civil versions of the aircraft currently in competition for the
Army utility tactical transport (UTTAS) mission.
North Sea Operations
There are numerous differences between support operations on the
Gulf Coast and those in the North Sea. The boats and helicopters used
: in the North Sea are generally larger, and aluost all of the crew changes
are accomplished w_th helicopters. The average trip lengths are greater,
and the maximumdistance a drilling rig can be located offshore Is often
it
I
1976010999-022
I
i
-20-
limited by helicopter range. Advance staging areas are often set up in
remote areas i00 to 150 miles from the main base, in order to effectively
extend the range of the helicopter. Spares support by helicopter is
much more important in the North Sea than in the Gulf of Mexico. Even
routine cargo is often carried by helicopter because weather conditions
prevent offloading from boats.
Natural gas is found in the southern North Sea, where offshore
distances are shorter and a hlgh-frequency short-range helicopter service
is required (more similar to that of the Gulf Coast). However, oil
support operations in the rugged environment of the northern North Sea
call for the largest helicopters now available. Two engines are required,
not only for overwater safety, but also for the carriage of loads weighing
two or three tons. Long range operations are conducted primarily with
the Sikorsky S-61N or S-58T, while the smaller Bell 212 and Bolkow Bo
105 are used on the shorter routes and for small parties.
Most of the lO0 or so North Sea helicopters are IFR equipped because
of the poor weather conditions. However, the unpredlctable and fast
changingweather means that a rig landing can never be guaranteed.
Therefore, payloads and distances are often reduced in favor of extra
fuel to enable the helicopter to fly to and from its destination without
refueling.
The average distance to the oil rigs is currently about 150 miles,
although some are in excess of 200 miles. (7) As oil exploration extends
further north, the avarage offshore distance will increase, and may
exceed 250 miles by 1985. This means that distances of greater than 250
miles will be common. Some oil companies are now considering drilling
1976010999-023
-21-
northwest of the British Isles at distances which would require aircraft
with an unrefuelled range approaching I000 miles. (II)
As offshore distances increase, aircraft capable of higher speed as
well as longer range are clearly needed. The workhorse of the North Sea
is now the S-61N which can carry 15 passengers about 200 miles. Nearly
50 are now in use in the area, and orders are still being placed.
However, with a cruise speed of only 138 mph, it takes over three hours
per round trip to some North Sea sites.
1976010999-024
-22-
LOGISTICS SUPPORT VEHICLES
Boats
Boats are used in transporting men and equipment primarily in areas
with calm seas. In the Gulf of Mexico, one operator uses 80, 90, or 100
ft. boats for crew change missions, and has boats up to 200 ft. for
supply operations. The lO0 ft. boats can be used in 95% of the Gulf
weather conditions, but the 80 ft. boats are usable only in fair weather. (20)
Use of boats is even more restricted in the North Sea, since weather
conditions there are among the worst in the world. During winter in the
northern areas winds exceed 20 mph 60 percent of th_ time. In an average
storm, seas of 50 to 60 ft. are encountered, with gusts of over i00
mph. Fog and heavy rain often reduce surface visibility to zero.
Figure I0, from reference 21, illustrates sea conditions on the day
after a storm. Boats used in this environment are generally quite
large, ranging to 200 ft. or more. Even so, six boats wert lost by
North Sea operators in 1973 due to extreme weather conditlons. (21)
Typical lease costs for the Gulf Coast boats are $650 per day (12
hours) for the i00 ft. size, and $500 per day for an 80 ft. craft. This
includes crew but not fuel or oii costs. Fuel usage is about 100 gel/hr.
for the I00 ft. boat, and 60 gal/hr, for the 80 ft. boat, with a current
average cost of $0.37 per gallon. The boats are leased for an entire
day, and one or sore trips are gads, depending upon the distance. An
extra charge is sads for usage over 12 hours.
About 30 passengers are carried on s typlcal crew change mission,
: although the boats are designed to carry 50 to 85 passengers. The bost_
say carry from $ to 20 tons of deck cargo in addition to the passengers.
J I
1976010999-025
-23-
Speed of the boats ranges from 22 knots with passengers only, to about
15 knots with full cargo load.
Helicopters
Considering currently available helicopters and those expected to
be in production during the next several years, there are about 30
.models to choose from. These range in slze from 3 to 44 seats, and from
about $50,000 to $6 million in price. Approxlmately one-half are U. S.
designs.
Characteristics of medium helicopters now widely used in offshore
petroleum support are shown in Table 1.(22) Table 2 lists comparable
data for helicopters currently in development. (II) Normml cruising
speeds of the older vehicles are in the range of I00 to 130 knots, while
the newer aircraft cruise at about 150 knots. The never helicopters
also are Benerally larger and offer longer range.
Figure 11 illustrates range/payload chazacterlstlcs for several
offshore hellcopters used in the North Sea. Note the requlreuent for a
30 minute fuel reserve, plus the need for 2 pilots and emergency equip-
ment for overwater operation. None of these aircraft were designed for
the long ranges typlcel of offshore operations in the North Seas, and
therefore lust undergo considerable payload reductlor to achieve requlred
operatlonal capabillty. Range extension may be gained by addition of
auxiliary fuel tanks, but this further reduces poyload, as indicated by
Figure 11.
The S-61N is the most popular in the North Sea because its size and
range best fit the mission requtresents. A disadvantage is its cruise
i
1976010999-026
1 1 t _ 1 1
I
-24-
speed of 120 knots, which results in a round trip time of over 3 hours
to some North Sea rigs. Although designed for about 30 passengers, the
S-61N is operated with only about 15 to 20 seats on the North Sea, and
can carry only 10 to 11 passengers to the rigs 200 n.mi. offshore. Some
operators have _tated a requirement for a successor which can carry a
minimum of 20 passengers over 400 n.mi. at a cruise sveed of at least
(11)150 knots.
Since the UTTAS derivatives (Boeing 179, S-78C) offer slightly
greater maximum range capability as well as modest speed increases, one
or both of these aircraft are likely to see use in the North Sea, and
purchase options have been taken by operators in the Gulf of Mexico as
well. With military protypes now flylng, these aircraft could be avtLlable
as early as 1978. Despite the performance improvements available with
these helicopters, however, the speed, range, and payload requirements
of the future may not be satisfied.
The S-76 and hll 222 ere two helicopters designed largely frr the
offshore o11 industry. That these are the first hellcopters In umny
years developed by Sikorsky and kll r_,ttrely with company funds and
primarily for the clvll u_rket attests to tbp promising market potential
for advanced helicopters. Alor4with the Aerospatiale Dauphin, these
aircraft are d_aigned to carry 10 to X2 passengers 300 to 400 n. ui. 8_
cruise speeds of over 125 knets. The S-76 can be fitted with two
ausilllary fuel tanks to increase maximum range from 400 to 600 n.ul.,
with a reduction in payload of four passengers. Theme aircraft will be
qore flexible and economical than present helicopters, but will still be
too mta11 for some offshore operations.
1976010999-027
• .....................................T........................................•..........T...................................................................."T...................................."r I
i1 i
i ' I
i
-25-
The S-65, a civil version of the CH-53, offers the greatest range
and payload of any civil helicopter in the planning stage. Designed to
carry 44 passengers 260 n.mi. at 150 knots, the S-65 can also carry 30
passengers 600 n.ml. However, development will not proceed without at
least 20 firm orders. (II) Two disadvantages are its price, which is
about $6 million, and its gross weight, which at 35,000 lb. may exceed
the structural li._ts of some offshore platforms.
Advanced VTOL Aircraft
With offshore distances increasing rapidly, means of extending the
range of support aircraft are required. At the same time, it is clear
that simply increasing engine size and adding fuel tanks provides only a
partial solution. Range can be improved, but speed _s only slightly
increased, and unit operating costs increase as aircraft productivity is
reduced by offloadlng passengers.
A more satisfactory solution to future requirements may be the
development of advanced VTOL aircraft with greatly improved cruise
i efficiency. This would permit significant range increases due to better
i fuel utilization efficiency, and would also provide increased aircraftproductivity through cruise speed increases. Potential benefits to the
petroleum industry include increased rig crew productivity (less time in
transit), better emergency evacuation capability, and faster parts
delivery. Benefits to the aircraft operator Include lower operating
costs and lower capital investment. The operating costs would be less
since higher aircraft productivity reduces per-mile charges for deprecla-
tion, insurance, and pilot pay, and since fuel expenses would be reduced.
Perhaps land base expenses couL also be _educed if the number of
1976010999-028
d
-26-
support locations were reduced. The aircraft fleet capital investment
would be less if the cruise speed increment permits a reduction in fleet
size proportionately greater than the price difference between the
advanced aircraft and the helicopter it is replacing.
Three promising advanced VTOL concepts are the lift/crulse fan, the
tilt rotor, and the compound helicopter These aircraft are very different
in appearance and performance, and in many ways represent a significant
departure from current helicopters used in offshore petroleum _upport.
Figure 12 illustrates representative designs of the three concepts.
The compound helicopter differs from conventional helicopters in having
a wlng and auxiliary propulsion system for cruise. The tilt rotor, on
the other hand, uses the same propulsion system for vertical operation
and cruise. With rotors mounted on the wing tips, the aircraft takes
off and lands like a helicopter, but the rotors may be z)tated 90°
forward for cruise like a turboprop. The llft/cruise fan aircraft
dispenses with rotors entirely by employing large fans and vectoring
nozzles mounted on the wing and in the fuselage for vertical takeoff and
landing. The fuselage lift fan is shut down for cruise flight, where
the wing lift/cruise fans are utilized as efficient high bypass engines.
Each of these concepts offers potential advantages to the offshore
industry. While the conventional helicopter is the most efficient in
hover, this is a relatively small part of the typical offshore mission.
High cruise efficiency is very important to long range capability, and
cruise speed is crucial to the economic productivity of the aircraft.
1976010999-029
.............' -_ ........................................._...................................T..............................f...........................................T...........................7 .........................................._.............................,I 1 I :I
-27-
Table 3 compares the estimated performance characteristics of
representative designs for these three VTOL concepts to those of a
future conventional helicopter. The data for all four aircraft were
taken from conceptual design studies conducted for military V/STOL
missions, and are not necessarily representative of designs optimized
for offshore oil application. The performance capabilities of these
aircraft are greater than that required for most current offshore
operations. However, the more demanding operations of the future will
likely require aircraft with all-weather capability and improved pas-
senger comfort in addition to increased range, payload, and speed. The
availability of data from the military aircraft studies thus permits a
preliminary analysis of the benefits cf advanced VTOL aircraft in future
operations.
The three rotorcraft were sized for a mission involvin8 several
hours in loiter and hover plus a 300 n.mi. cruise. The available fuel
capacity, in combirmtion with good cruise efficiency, therefore provides
range capability much greater than that of any helicopter now in use.
The cabin size is sufficient for 23 passengers plus a crew of three,
although three crew members are not required to operate the aircraft.
Performance estimates for the offshore oil mission indicate unrefuelled
operation with 23 passengers to rigs at the round trip distances shown
in Table 3. _23)"" Hore distant operations would require payload reduc-
; tions in exchange for additional fuel.
The lift/cruise fan aircraft was sized for a transport mission of
: _ 2000 n.mi. with a 3600 lb. payload including STO takeoff and vertical
1976010999-030
-28-
landing. Maxkmum gross weight is 44,800 lb. for STOL operation and
34,500 for VTOL. With vertical takeoff the fuel load is reduced by
nearly 60%, which decreases the range to about 700 n.mi. for full
payload. Since most offshore petroleum operations could include STO
takeoff at the land base combined with VTOL operation at the offshore
rig, the unrefuelled range is about 1300 n.m. with 23 passengers.
The three rotorcraft designs were developed by the same contractor,
(24)and all represent similar advances in component state of the art.
That is, all employ hingeless rotors with composite blades, conventional
metal structure in primary airframe components, moderate use of composites
in secondary structure, and fly-by-wire control systems. The lift/cruise
(25)fan data are from a design study by a different contractor, but
represent generally similar component technology levels except that the
engine technology is less advanced.
The conventional helicopter is the simplest, lightest, and least
expensive of the four concepts. However, it is also the slowest and
least productive, and offers the lowest growth capability.
The compound helicopter provides greater speeds than the conventional
helicopter but incurs a weight and cost penalty due _o the wing and
auxiliary propulsion system. The productivity increase is offset by the
higher aircraft price, resulting in a higher unit operating cost. The
concept was eliminated from further consideration for the offshore
mission.
Figure 13 compares the unrefuelled range-payload performance of the
lift/cruise fan and tilt rotor to that of the advanced helicopter. The
J
1976010999-031
-29-
aircraft direct operating costs versus radius are shown in Figure 14.
The overall productivity of the two faster aircraft is much greater than
that of the helicopter, and per-mile operating costs are less than those
of the helicopter despite the higher hourly costs.
Both the tilt rotor and lift/cruise fan aircraft offer superior
economics for operations more than 50 to 75 n.mi. offshore, and the
lift/cruise fan appears most economical beyond about 250 n.mi.
There are numerous factors which could alter the indicated cross-
over points, so caution must be exercised in drawing conclusions from an
analysis of this type. For examplejdifferences in the weight and cost
estimating methodology used by the two contractors could easily change
the estimated price of either aircraft by 20% or so. This would directly
impact depreciation and insurance charges, which represent about 30% of
the DOC.
Confidence in the cost and performance estimates of the helicopter
is greatest since it is the only one of the three concepts for which
operational vehicles have been built. Aircraft development costs and
maintenance manhours per flight hour are less certain for the other
designs, although an attempt was made to rellstlcally account for the
economic penalties associated with the greater compalexlty of the tilt
rotor and lift/crulse fan.
; The range growth capability of the tilt rotor is the greatest of
any of the four concepts due to its very low fuel consumption in cruise.
The importance of this long range capability may be greater than is at
first apparent. With a radius of operation roughly twice that of
• i+
1976010999-032
..................._ ................ _.................. _...............................T........................................_.................................t...................! ......................_..................' ........
1i
-30-
helicopters, a tilt rotor could support petroleum exploration much
further offshore, and could possibly contribute to a greatly expanded
availability of energy in the 1990's. In the North Sea especially,
drilling plans are now limited by the range capability of available
(ii)helicopters.
A potential disadvantage of the tilt rotor is the existence of
large rotors at the wingtips. The total tip-to-tip width with rotors
turning is 85 ft. for the 23 passenger model compared to rotor diameters
of 62 feet for the S-61N and 72 ft. for the S-65. This may cause a
landing clearance problem on some drilling rigs, but would probably not
pose a problem on the larger rigs or on production platforms, which
usually have no superstructure. Presumably this problem could be
resolved by modifications to the landing platform if the advantages of
the tilt rotor are sufficient.
The lift/cruise fan offers a significant advantage in speed capability
over any of the other VTOL concepts. With high wing loading and normal
cruise at about M 0.75 it offers passenger comfort and trip times approaching
those of conventional Jet transports. The aircraft weight and purchase
price is greatest of any of the concepts, and fuel utilization efficiency
is between that of the tilt rotor and helicopter.
Figure 15 compares the direct operating cost of the S-61N, with and
without offshore refuelling, to that of a future tilt rotor or llft/crulse
fan, based on slmilar assumptions for fuel price, maintenance labor
rates, etc. Due to uncertainties In the ultimate price and maintenance
requirements of the yet undeveloped advanced VTOL aircraft, a sensitivity
analysis was run to determine the impact of a 50% increase in both
i
1976010999-033
-31-
aircraft purchase price and maintenance manhours per flight hour. The
result is the DOC band shown in Figure 15. Whereas the DOC of the S-61N
increases with range due to the offloading of passengers, the advanced
aircraft economics would continue to improve with distance out to its
design range. This figure suggests that advanced VTOL aircraft would be
superior for offshore distances over i00 n.mi. regardless of the concept
selected or the accuracy of the present cost projections.
The productivity of the S-61N and the advanced aircraft are compared
in Figure 16. The higher speed aircraft perform more missions per day,
and hence could transport more passengers. This productivity advantage
ls enhanced as range increases, since the S-61N must trade payload for
fuel. The faster aircraft would permit a significant reduction in the
number of pilots and in the required investment in aircraft, spare.s, and
,. ground support equipment. The higher productivity would also be important
in the evacuation of large numbers of oilmen prior to major offshore
storms, an occasional requirement.
7
|
1976010999-034
-32-
BENEFITS OF ADVANCED VTOL AIRCRAFT
In a study of the potential application of advanced aircraft to the
offshore mission, several factors must be considered. These are: i)
the capital required to provide the new VTOL aircraft; 2) the productivity
and operating costs of the new aircraft compared to existing helicopters;
and, 3) benefits to the petroleum industry resulting from the special
characteristics of the aircraft, such as improved range, speed, or
payload capability.
The Gulf of Mexico and the North Sea were selected for this analysis
because extensive use of helicopters in these areas provide a data base
with which to make realistic comparisons. There is much uncertainty
regarding the payload size and range for which concepts such as the t_it
rotor and lift/cruise fan could effectively complete with advanced
helicopters. However, it appears that such aircraft would offer the
most advantage in crew change and cargo movement operations, where the
higher aircraft weight and price can be offset by higher productivity.
Small helicopters used for short hops and for transportation of execu-
tives and specialists are less likely to be replaced by other aircraft
concepts. There will, of course, be a strong market for advanceg
helicopters which offer greater speed and operating economy than the
hundreds of small helicopters now used in offshore operations.
Gulf of Mexico
More than 4000 oilmen are moved by helicopter every day in the Gulf
of Mexico. The total cost of running the fleet of 300 hellcopters is
estimated to be at least $40 million per year, based on an analysis of
i,
1976010999-035
-33-
the expenses of two of the largest operators. Advanced helicopters and
VTOL aircraft can provide DOC reductions of as much as 30% to 50% at the
current 75 to 130 n.mi. offshore distance typical of Gulf operations.
This indicates a potential annual savings of $12 to 20 million, at the
present rate of offshore activity, with replacement of the entire fleet.
Of course, such replacement would be gradual even if the advanced alrcraft
were available now.
The savings to the aircraft operator is due to the increased aircraft
productivity. There are additional benefits of high speed aircraft
which would accrue directly to the petroleum industry. Reduced travel
time would increase the productivity of the oilmen. This time value may
be only $2.60 per hour for those companies paying minimum wages to crews
in transit, but would be much higher for those paying full wages. In
addition, managers or specla]Ists making on-site inspections would
generally be travellng during normal working hours and thus at a high
time value.
A complete measure of the total benefits of high speed aircraft
would include spares support and emergency operations since a lower down
time yields a higher rig productivity. Although it is a consideration
in the current use of helicopters, there was not sufficient data to
include this in the present benefits analysls. Only the savings due to
aircraft operating costs and oll worker productivity were included.
The ten year benefits due to the introduction of advanced VTOL
aircraft in 1985 are compared In Table 4. The benefits in this table
reflect only the medium helicopter market. Savings in aircraft expenses
and oilmen salaries due to introduction of new small helicopters are not
i included.
1976010999-036
L
I
-34-
[t was assumed that the average offshore distance of :igs served by
the larger aircraft will increase to 130 n.mi. in the decade after 1985.
This appears to be a very conservative estimate in light of current
trends. It was also assumed that the number of passenger round trips
for crew change operations would increase from about 22,000 per month
now to an average of 60,000 per month in the 1985 to 1995 time period.
This represents a 7% average annual increase, considerably below recent
growth rates in offshore activity.
The estimated number of aircraft required reflects a i00 hour per
month average utilization and an average of 15 passengers per trip,
which is a 65% load factor for the 23 seat aircraft. In contrast, only
i0 passengers can be carried this distance by the S-61N (without refueling).
The required capital investment for aircraft and spares (25% of aircraft
price) is listed for comparison, and it should be noted that the high
speed aircraft provide a 30% to 50% reduction despite a higher unit
price. These values were not added to the ten-year benefits since the
aircraft DOC already includes a depreciation term which amortizes the
investment.
The oil worker productivity gain in Table 4 is the total ten-yesr
wage savings reallzed by transporting crews to and from the offshore
rigs once per week with advanced aircraft instead of current hellcopters.
The transit tim value of each worker was assumed to be $2.60 per hour.
Not included in the table is another $30 million or so which could be
saved over a ten year period by transporting hish-time-value personnel
during normal working hours ra small advanced hellcopters.
)
|
1976010999-037
/
-35-
The total indicated benefit over a ten year period for converting
to the advanced aircraft is significant, ranging from $514 million for
180 knot helicopters to $661 million for the lift/cruise fan. The tilt
rotor and lift/cruise fan provide nearly equal benefits at this offshore
distance. No attempt was made to estimate the benefits of a mixed
fleet, although a realistic assessment would indicate that some of each
aircraft type are probably desirable for operational flexibility.
Neither the tilt rotor nor the lift/cruise fan are operational
aircraft concepts, and much technology development is necessary to
permit realization of the indicated benefits. Although the acceptability
of a concept to the user community cannot be predicted with certainty, a
simple comparison can be made of the investment value of each aircraft
type to evaluate the likelihood of it being used if available. The
savings in aircraft operating cost become pre-tax profits to the aircraft
operator assuming constant _evenue for passengers hauled. The ability
of the advanced aircraft to generate increased operating profits with a
reduced capital investment indicates that these concepts would be very
attractive to the aircraft operators.
The growth rate in offshore transportation requirements is very
uncertain. This Ib true for several reasons: (1) the future pace of
offshore petroletm activity is uncertain due to economic and political
considerations; (2) frequency of crew Iotation _ay change; (3) developments
in petroleum production and drilllng technology may alter the number of
_en required to operate the rigs. The average offshore distance is also
uncertain due to unknowns in future drilling technology, and because the
exploration cost increases greatly in deeper water.
L.i_. i
1976010999-038
-36-
For all of these reasons, the annual benefits for each aircraft
type were computed as a function of both average distance and passenger
demand. The result is shown in Figure 17. The band for each offshore
distance represents the range of benefits from the advanced helicopter
(lower line) to the tilt rotor and lift/crulse fan (upper line). The
width of the band is the potential benefit of the lift/cruise fan or the
tilt rotor in a comparison with advanced helicopLers. The benefits
shown are relative to the Bell 212 at 90 n.m. and relative to the S-61N
at 130 n.m. and 220 n.m. This is because the Bell 212 is more economical
at the shorter range, but the S-61N would most likely be required for
the greater distances. Note that even with very modest growth in transportation
requirements the advanced aircraft would provide significant annual
benefits to the industry.
North Sea
Nearly one-half of the estimated 100 helicopters currently operating
in the North Sea are S-61N's, with an operating cost of about $560 per
hour. Since the other 50 helicopters are smaller, the average cost for
the entire fleet may be about $400 per flight hour. At an average
utilization of 80 to i00 hours per month the annual cost of providing
helicopter service to the offshore rigs is estimated to be $40 or $50
million.
Figure 16 indicates t.hat advanced VTOL aircraft could reduce the
expense of operations to the more distant rigs (about 200 n.mi. offshore)
by either 60Z or 3OZ, depending upon the weather. If a rig landing can
not be guaranteed, the S-61N passenger complement must be reduced to 10,
with a very high cost per passenger-mile. If, however, good flying
i
1976010999-039
r "r,..............................._..............................T .................................T ...._ ........ ............v ...................................._ ....................
-37-
conditions and fuel availability on the rig assure that the S-61N can be
refueled for the return flight, 17 passengers can be carried and the cost
per passenger-mile drops from 52¢ to 32¢. Even so, the advanced VTOL
would have a large economic advantage at 17¢ per passenger-mile. This
suggests that total savings achieved by replacing the current S-61N
fleet alone could reach $I0 to $15 million per year.
Table 5 compares the estimated benefits of the advanced _4rcraft
to the S-61N for 1990 operations in the North Sea. Note that the average
offshore distance projected for 1990 is greater than that in the Gulf of
_exico, as it is now. The assumed passenger demand is also greater than
in the Gulf for two _easons. First, North Sea oil exploration is at a
much earlier stage of development, and thus can be expected to show a
greater rate of growth. In addition, many North Sea workers now remain
on the rigs for two weeks at a time, but crew rotation is expected to
occur weekly by 1985. (12) Assuming a net growth of llZ per year yields
a total passenger demand of 75,000 round trips per month in 1990, compared
to an estimated 12,500 in 1973.
The combination of the high traffic level and the greeter offshore
distance leads to a potential savings of about $2 billion for the ten
year period with replacement of S-61N helicopters by advanced VTOL
aircraft. Although the S-61N is the most popular North See helicopter
today, it is unlikely that it would be used for the rang° indicated
because of its performance limltetions. A more realistic comparison
would be against improved helicopters such as the UTTAS derivatives,
which are expected to be aveileble about 1978. In this case, the indicated
benefits would be much less, as Table 6 shows.
,L
1976010999-040
-38-
The UTTAS derivatives appear well suited for many North Sea operations
with ranges of 350 to 400 n.m. at a payload of 20 or more passengers.
Auxiliary fuel tanks are required for unrefueled operation to rigs more
than 200 n.m. offshore, however, and the advantages of the advanced
aircraft would increase for the more distant rigs. The indicated
benefits in Table 6 are conservative, as the UTTAS is near maximum
payload for that radius, while the advanced aircraft are being operated
at a 65% load factor.
|
I,,,_-
1976010999-041
-39-
CONCLUSIONS
The worldwide need for energy is creating a tremendous expansion in
offshore petroleum activity despite the high costs involved. As imprev_d
drilling technology permits recovery of oll and gas from deeper waters
the offshore distances will continue to increase. This will complicate
the logistics support required to maintain the flow of men and materials
to the rigs, and will greatly increase the number of vehicles needed.
Marine vessels provide a variety of support functions, including
towing, pipeline laying, cargo supply, and personnel transportation.
The use of helicopters is growing rapidly for personnel movements
because of superior speed and comfort. The fast response of helicopters
in emergencies is also important to safety and to maintaining high rig
productivity. With the ability to reach rigs 200 miles offshore in
about 1.5 hours, the helicopter economics and general suitability for
many operations are superior to those of boats, which would take more
than i0 hours. This advantage is enhanced in rough weather such as that
of the North Sea, where operation of boats is difficult.
As offshore distances increase, the size of the rig crew tends to
increase, both because of increased rig sophistication and because it
becomes economical to keep more specialists aboard. The trend in
_ helicopter purchases is toward ifrger aircraft in order to provide the
increased range and payload capability required. Greater speed is also
sought as a means of further increasing the aircraft productivity.
_' Current helicopters provide relatively poor cculse efficiency,
which limits maximum speed and range. The passenger load must be severely
1976010999-042
-40-
reduced to provide sufficient fu¢l to reach the more distant rigs. This
greatly increases the unit operating cost and the number of aircraft
required.
Offshore refueling stations would extend the range capability of
helicopters, but this would further increase trip time and operating
costs. Many operators do not permit offshore refueling on manned rigs
for safety reauons.
A need clearly exists for advanced helicopters with greater cruise
efficiency. Helicopters now in development will provide better range/payload
capability as well as 20% to 30% increases in cruise speed. This will
provide significant improvements in operating economics. Further gains
are possible through advanced helicopter technology now in progress.
Future petroleum activity 200 to 500 miles offshore will require
even greater improvements in VTOL aircraft efficiency. Concepts such as
the tilt rotor and llft/cruise fan are very promising. Due to good fuel
utilization efficiency, greatly extended range of operation is possible
without refueling. The cruise speed of these concepts is also greater
than that of either current or advanced helicopters. The tilt rotor
provides nearly twice the range of the helicopter for the same fuel and
trip time. The lift/cruise fan cruises at three times the speed of the
helicopter and also yields a greater range/payload capability.
The greater productivity of the lift/cruise fan and tilt rotor
would permit reductions in fleet size, with lower capital investment in
aircraft, spares, ground equipment, and pilot trainlns. Aircraft direct
operating costs may be significantly less than those of current helicopters
1976010999-043
I'
-41-
at offshore distances above 59 to i00 miles. The faster aircraft would
provide several other advantages, including better emergency evacuation
capability, faster parts delivery in times of unexpected rig shutdown,
and increased crew productivity through reductions of time in transit.
Despite a higher purchase price the per-mile costs of the high
speed aircraft would be very attractive, even in a comparison with
advanced helicopters, at the ranges likely in future offshore operations.
However, uncertainties in future offshore requirements and in the ultimate
values of aircraft price and maintenance cost for concepts still in the
technology development phase preclude a selection of any one preferred
concept at this time.
Each VTOL aircraft type has a role to fill in future offshore
logistics operations, as does the boat. Tilt rotors or lift/cruise fan
aircraft cannot economically replace helicopters in the short-range
operations. There will be a continuing need for advanced helicopters
for movement of small parties of executive and specialist personnel
during on-site inspections, and for crew change operations on the many
rigs close to shore. The more distant operations will best be performed
with either the tilt rotor or llft/crulse fan, or possibly with improved
compound helicopters. The ideal fleet would consist of some mix of the
different aircraft concepts.
iI ....................T............. ""r ..................................._r..............;....... T
i
1976010999-044
-42-
REFERENCES
i. Tile Orange Disc., a Gulf Company Pulication, 3uly-August 1975,
2. National Petroleum Council, "U. S. Energy Outlook", December 1972.
3. Rockefeller, David "Financial Aspects of the Energy Crisis,"
American Gas Association Monthly, December 1974, pp. 29-31.
4. Jackson, J. R., "Worldwide Offshore Petroleum - Importance and
Ownership Acquisition," A. G. A. Monthly, December 1974, pp. 16-19.
5. Abelson, Philip, "Energy Supply and Demand During the Next Decade,"
A. G. A. Monthly, December 1974, pp. 12-15.
6. "Vertol Explores BO.105 Growth Versions", Aviation Week and Space
Technology, Sept 16, 1974, pp. 57-59.
7. "Civil, Military Demands Spur Helicopter Growth Surge", Aviation
Week and Space Technology, Sept. 29, 1975, pp. 20-34.
8. International Oil and Gas Development - Yearbook 1974, Part I,
Vol. XLIV, U. S. Offshore, p. 123.
9. "Hughes Rig Count," Oil and Gas Journal, October 6, 1975.
I0. "Report-CEQ Hearings on Offshore Drilling," A. G. A. Monthly,
March 1974, pp. 7-10.
Ii. Broadbent, Stephen, "Oil Support Helicopters", Flight International,
August 14, 1975, pp. 229-234.
12. International Oil and Gas Development - Yearbook 1973
Part II, Vol. XLIII, Europe-North Sea, p. 468.
13. International Oil and Gas Development - Yearbook 1974
Part II, Vol. XLIV, Europe - Norway, p. 505.
14. Personal communication with Mr. Arthur Bondraux, of Chevron
Oil Company, July I0, 1975.
15. Personal communication with Mr. Phil Mayhew of Air logistics inc.
October 2, 1975.
16. "Industry Future Keyed to Civil Market", Aviation Week and Space
Technology, September 29, 1975, pp. 39-45.
17. "Demand Cortinues Strong on North Sea", Aviation Week and Space
Technology, September 29, 1975, pp. 46-47.
18. Apps, John, "Bridge Over Troubled Waters", Rotor and Wing, January-
February, ].974, pp. 24-28.
|
1976010999-045
-43-
19. Petroleum Helicopters Inc., 25th Annual Report, 1974.
20. Personal communication with Mr. Jerry Blankinship of OffshoreGeneral Inc., October 3, 1975.
21. Offshore Logistics, Inc., 1974 Annual Report.
22. "Civil Helicopter Specifications", Rotor and Wing, Sept/Oct. 1973
pp. 24-29.
23. Smith, Keith, et. al., Preliminary Data From NASA Contract
NAS2-8710, "The Applications of Advanced V/STOL Aircraft Concepts
to Civil Utility Mission3", The Aerospace Corp., October 24, 1975.
24. "Navy Medium VTOL Design Study", Boeing Vertol Report D 210-10727,February 1974.
25. "Design Definition Study of a Lift/Cruise Fan Technology V/STOL
Aircraft" McDonnell Douglas Report MDC A3440, NASA CR-137678,June 1975.
i
i Iio
] 9760] 0999-046
¢.=0 o ¢'_ ur)=_1_.. o c_ ,It- o_ co o ,-"_-.4o Od 0 _t" ¢'_ ¢'_ ¢XJ i._ --LU ,--- " P',, _ r-- C,J
o t'_ o
•, i._ r-- r.- cM
i=,=,.
1976010999-047
i
-_"T ......._ ......................, ............'_'""_ .........................T"_""_""'_ '- T...................• ................._1................-_r--_ ...... "_r............
1976010999-048
LLJI'-- -JI _1" CM
Z 0 I"l O_ (:3 Q (_ 0 Q P-
"_ --J_ I CM P-.-
Z _
"_°I'-o o ,,-,0 C) I--- CO P- (_ I._ O_ I_
I'_ (:0 _ ('_ 0 0 O0 0r,_ (M 0 0 0
I--
C_ _
N
................ 1"................... T ................ 1' .................. 1"_ ............. "?"'""'_"_" _ ""_f"' ............. "" ...........,..................... ,' '"" ..... ,
1976010999-049
I
i1
I i 1 I -I
1976010999-050
•=_ ,,win
1976010999-051
_J
..................I..... _ ............ T ................T...................................._.......*_................_............................_......................_........
1g76010ggg-052
I _ _ i 1 1 1 ?
PRI_EDING PAGE BIdLNK NO'EJ'JD,JO_q
1976010999-053
0 50 100I
MITES
;AN FRANCISCO
Figure 2.- Offshore petroleun,activity off the tl.S. Pacific Coast.
J
#4
............. • ',le ................. _ ............. T .......... T ........... • ................ r ............... • ...............
1976010999-054
! T 1 1 1 ?
ARC " OCEAN
Figure 3,- Offshore petroleum activit)' along the Southern Alask: Coast.
i all............. _ ............ ii-rllrll ii1[ ii _11T _ - ii I iflll[ii ............................... r ..... ,
m,,,m,m,,,,m,f,,,m "_"'£'_ ......."-""'-'"r ............................."f...................... _'.........................................v................ v.................. ,........ , ....
1976010999-055
I
!i
PROVIDENCE
GEORGESBANK
NEW YORK CITY BASIN
t.,. BALTIMORECANYON
!WASHINGTON BASIN
NORFOLK u_
'CHARLESTON=
SAVANNAHBLAKEPLATEAU
;,,_ JACKSONVILLE BA
0 100 200I
MILES
_ POTENTIAL OILAND GAS AREAS
;"
Fzgure 4,- Potential oil and gas sites alon£ the U, S, Atlantic Coast.
1976010999-056
1 T 1 !
MAGNUS l
+ t X�I°o..,++,*"'_'_ I
T"NI' ¢'f ICORMORANT • • STATFJORD |
., I++)I--NT I":-'*""s++i -+.o.o. I
_I /y_' NINIAI_" 4" I
SHETLAND IS. _ _,,-- ////" I
.aam( p _,_' //_ , ALWYN I
t_cm i. _ m-_._,,_._ mr,L41RFwrdmwI _ _ i
4" ir_ SUMBURGH I+ I
BERYL Io_. ,s.___ I
"t_._-_........_,_,,,,,,,{,,,_ + i
. PIPER
_*,_,_,___.*._,,,. . + ANDREW n_. _'; U:_,_:, ",, ..'% . ..ih FORTIES l
_,'. '..,:_, '___ ABER OEEN _ l
: _.. ,,_.'_",_ , FLOUNDER
: _ .'.,...,,'_' .... ." :',.;'r ,c - .._',, ,'" JOSEPHINE,
' ;'_" _':' _"' ,,6 LJ'¢I ''$" " _ _ AUK •
• : ,-":,,_ "';: " _,;.":_".'_' "_ ,,_¢_m ,t''.'_- ARGYLL
"', _ -,. _ r_ " " _- _" • • _._v v w IIJ_GI
__': - :';,?": .: :-_ MULES• _',':,;' . ,'- ' ........ ",," _OILFIELD + DRILLING SITE-1975 '_
Figure S.- North Sea petroleum sites served by BritLsh helicopters,
• /?
1976010999-057
0 100 200 SHETLAND NORWAYi 1
MILES SUMBURGH:
NORTH
.-, "-DENMARK
,. ".L.---. CURRENT". _--.-. ACTIVITY
__ ---_-' _ ." UNITED;KINGDOM
GERMANY
NETHER LANDS ""
Figure 6.- Offshore petrolcum activity in the North Sea.
1976010999-058
o-o
J
1976010999-059
1976010999-060
1976010999-061
C)RTGINALl__OFPOOR_UALIT_
1976010999-062
ii
1
1976010999-063
_' t 1 1
,t
1
1976010999-064
/1f
/ _8 °
_._ o.-j
0
_ °CE0
R
0
- _8 '.am
_' I I I
_, SNION3SSVd NrlINIXVIN
1976010999-065
, i_
1976010999-066
1976010999-067
l I I I i I
AVO UnOH _1.kl3d SIV3S dlldl ONnOU 3"IHV'IIVAV wrl_llXVIN
1976010999-068
NOI'I'IIW $ '1t::I3N38 _VrlNI_N 1V101
I
t
1976010999-069
Recommended